Roller device with instrumented ball bearing

ABSTRACT

A roller device with instrumented ball bearing of the type supported by a non-rotating element and provided with a sensor of rotational parameters, characterized in that the ball bearing ( 2 ) and the sensor elements ( 4 ) are rigidly mounted on a fixing element ( 3 ) adapted to co-operate with another mechanical member for fixing the device.

The present invention relates to the field of rolling bearingassemblies, particularly those designed for rollers or pulleyscomprising a fixed part intended to be mounted on a support or a frame,and a rotating part intended to come into contact with an externalelement such as a belt, a rail, a drum, etc. Said external elementdrives the rotation of the rotating part which is mounted so that it canrotate freely on the fixed part.

Rollers may be used in many applications. Thus, one findsbelt-tensioning rollers intended constantly to exert a tensile force ona belt. The rotating part in contact with the belt consists of the outerring of a bearing or of a pulley mounted on said outer ring.

Rollers may also be used as guide members for guiding elevator doors orescalator handrails.

Increasingly, the operation of moving mechanical assemblies iscontrolled by electronic systems, and this assumes that the necessaryinformation about the moving members, particularly the movement, speed,acceleration, etc. thereof is permanently available.

If a roller is equipped with a device for detecting rotation parameters,then information about the angular or linear movements of the elementsin contact with the rotating part of the roller can be deduced fromthis. For example, if the roller bears against an escalator handrail,then it is possible, via the roller, to determine the linear speed ofthe handrail. Likewise, by instrumenting elevator door rollers, it ispossible to obtain information about the linear movement of the doors,such as the speed, the acceleration or the travel.

In devices of the prior art, the detection systems with which therollers were equipped were attached to existing rollers and requiredcomplex and often expensive adaptations.

Document FR-A-2 626 631 describes a rolling bearing assembly setup witha sensor device which has significant axial bulk and contains a highnumber of parts, especially special-purpose parts.

The invention proposes to remedy the disadvantages of the prior art.

The invention proposes a preassembled instrumented roller module thatthe end-user now need merely mount very simply on a support.

The roller device with instrumented rolling bearing, according to oneaspect of the invention, is of the type supported by a non-rotatingelement and provided with a sensor means for sensing rotation parametersand with an encoder means. The bearing and the sensor means are mountedrigidly on a fixing element able to collaborate with another mechanicalmember with a view to fixing the device. The fixing element comprisesmeans of securing to said other mechanical member, these means beingprovided in a central position. The encoder means is fixed directly tothe bearing.

Various sizes may be anticipated to cover a wide range of applications.Because of the compactness and simplicity of the instrumented rollers,the same size will be suitable for many applications.

Advantageously, the fixing element has a cylindrical outer surface incontact with the bore of an inner ring of the rolling bearing.

In one embodiment of the invention, the rolling bearing comprises aninner ring, an outer ring, a row of rolling elements, for example balls,arranged between the inner and outer rings, and a cage for maintainingthe circumferential spacing of the rolling elements. Furthermore, a sealor sealing flange may be fixed on one of the rings and extend into theproximity of or into contact with the other ring.

Advantageously, the sensor means comprises an annular support body andat least one sensor element. The body is arranged in contact with alateral face of the rolling bearing.

In one embodiment of the invention, the fixing element comprises acentral through-hole able to take a screw. The sleeve tube may bearranged in the bore of the inner ring.

In one embodiment of the invention, the sleeve tube comprises an outersecond surface in contact with an inner surface of the sensor means, forexample of its support body, and a radial surface in contact with aradial surface of the inner ring of the rolling bearing. The sleeve tubeand the rolling bearing can thus be positioned axially.

In one embodiment of the invention, the fixing element comprises a meansfor axially holding the support body. This holding means is preferablyrigid.

In one embodiment of the invention, the sleeve tube is provided with aplain or threaded bore for fixing the device to another mechanicalmember. The sleeve tube is thus able to collaborate with a screw passingthrough it and which collaborates with a threaded bore of said othermechanical member or collaborates with the screw threads formed in thebore of the sleeve tube.

In one embodiment of the invention, the fixing element and the supportbody form one single piece which may advantageously be made of a rigidsynthetic material, for example a fiber-filled material.

In another embodiment of the invention, the fixing element and thesupport body form distinct parts.

Advantageously, the support body is provided with a radial lateralsurface in which there is formed an annular slot comprising acylindrical outer surface, the sensor element lying flush with saidcylindrical outer surface.

In one embodiment of the invention, the device comprises an encodermeans provided with a support and with an active part, the active partprojecting from a lateral face of the rolling bearing, the support beingfixed directly to the bearing. The active part is arranged radially atthe rolling elements.

In one embodiment of the invention, the encoder means and the sensormeans are mounted in close proximity to a lateral face of the rollingbearing. The device is thus axially very compact.

In one embodiment of the invention, the fixing element comprises aradial surface for mounting on a support, the encoder means beingarranged axially between said radial mounting surface and the rollingbearing. The encoder means is thus well protected and prevented fromprojecting axially from the pulley or the bearing.

The fixing element may be provided with a threaded axial portionprojecting from the radial mounting surface.

In one embodiment of the invention, the device comprises an additionalrolling bearing mounted on the fixing element. This is well suited tolarge rollers and/or rollers subjected to heavy loads and/or highlyinclined forces. A spacer piece may be arranged between the bearings, attheir inner rings or their outer rings. The spacer piece may be aseparate element or be incorporated into the pulley or into the fixingelement. As a preference, the additional rolling bearing is of theuninstrumented type.

The present invention will be better understood and other advantageswill become apparent from reading the detailed description of a fewembodiments taken by way of nonlimiting examples and illustrated by theappended drawings, in which:

FIG. 1 is a view in axial section of a rolling bearing assembly mountedon a frame;

FIG. 2 is a view in perspective of the rolling bearing assembly offigure 1, not mounted on the frame;

FIG. 3 is an alternative form of figure 1;

FIG. 4 is a view in axial section of a rolling bearing assembly equippedwith a pulley; and

FIG. 5 is a view of another embodiment.

As can be seen in FIG. 1, the instrumented rolling bearing assemblyreferenced 1 in its entirety comprises a rolling bearing 2, a fixingelement 3 and a sensor assembly 4. The bearing assembly 1 is mounted ona support 5 by means of a screw 6.

The rolling bearing 2 comprises a rotating outer ring 7 provided with araceway 8 on its bore, an inner ring 9 provided with a raceway 10 on itsouter surface, a row of rolling elements 11, in this case balls,arranged between the raceways 8 and 10 of the outer 7 and inner 9 rings,and a cage 12 for maintaining the circumferential spacing of the rollingelements 11. The cage 12 may be made of synthetic material. The rings 7and 9 of the bearing 2 are of solid type, produced by machining, butcould also be made of pressed sheet metal. The outer ring 7 is provided,on its bore, near one of its lateral surfaces, with an annular slot 13.A sealing flange 14 is mounted in the slot 13 and has a free endextending as far as the vicinity of the outer cylindrical surface of theinner ring 9.

In the embodiment depicted, the outer ring 7 rotates and the inner ring9 does not. However, the reverse arrangement could perfectly well beanticipated.

A slot 15 is formed in the outer ring 7 symmetrically to the slot 13with respect to a plane passing through the center of the rollingelements 11.

An encoder assembly 16 is mounted secured to the outer ring 7. Theencoder assembly 16 comprises a support 17 of annular shape with anL-shaped cross section with a radial part the free end of which ismounted in the slot 15 and a tubular part running from the inner end ofthe radial part away from the rolling elements 11, in other words towardthe outside of the rolling bearing 2. The support 17 may [lacuna] madeof metal, for example of light alloy, and be push-fitted onto the outerring 7.

The encoder assembly 16 further comprises an active part 18 mounted onthe outer surface of the tubular part of the support 17 and formed, forexample, in elastoferrite, that is to say a nitrile-based mixturecontaining magnetized ferrite particles. A skeleton 19, for example madeof thin sheet metal, supports the active part 18 overmolded on top ofit. The skeleton 19 is push-fitted onto the tubular part of the support17. The encoder assembly 16 projects axially from the bearing 2 towardthe support 5.

The fixing element 3 is of annular overall shape, here in the form of asleeve tube. The fixing element 3 comprises a bore 20 provided with athreaded portion 21 at one of its ends, and an outer surface having afirst cylindrical portion 22 arranged axially on the opposite side tothe threaded portion 21 of the bore 10, then an annular rib 23, then asecond cylindrical portion 24, then an annular rib 25 arranged axiallyon the same side as the threaded portion 21 of the bore 20. The two endsof the bore 20 are open.

The fixing element 3 is mounted in the bore 9 a of the inner ring 9 ofthe bearing 2 with the first cylindrical portion 22 in contact with thebore 9 a and the rib 23 in contact with a radial surface 9 b of theinner ring 9. Provision may be made for the inner ring 9 and the fixingelement 3 to be mounted as a fairly tight fit, so that they are heldtogether by push-fitting.

Finally, the fixing element 3 is provided with a radial end surface 26on the same side as the threaded portion 21 of the bore 20. The radialsurface 26, axially offset outward with respect to the support body, isin contact with a disk-shaped surface 27 belonging to the support 5,formed as a slight hollowing with respect to the rest of the support 5,so that the fixing element 3 is positioned radially with respect to saidsupport 5. The support 5 is provided with a through-hole 28 aligned withthe bore 20 and with a diameter greater than or equal to the latter. Thescrew 6 is provided with a head 29 arranged in contact with the support5 on the opposite side to the bearing assembly 1 and with a body 30 witha threaded outer surface passing through the hole 28 and engaging withthe threaded portion 21 of the bore 20 of the fixing element 3.

The sensor assembly 4 comprises a support body 31, for example made ofsynthetic material, having an annular overall shape with an innersurface coming into contact with the second cylindrical portion 24 andthe ribs 23 and 25 of the fixing element 3. The support body 31 is ashape match for said cylindrical portion 24 and said ribs 23 and 25,guaranteeing the relative axial positioning of the fixing element 3 andof the encoder assembly 4.

The support body 31 is provided with a radial surface 32 in contact withthe radial surface 9 b of the inner ring 9. An annular slot 33 is formedin said support body 31 from the radial surface 32 and is therefore opentoward the bearing 3, so that it can house the part of the encoderassembly 16 which projects axially from the radial surface 9 b of theinner ring 9. The slot 33 is provided with a cylindrical outer surface34. A sensor element 35 is mounted semiembedded in the support body 31and lies flush with the cylindrical surface 34, so that it is mountedfacing the active part 18 of the encoder assembly 15 and with a smallradial gap from said active part 18. The sensor element 35 is of themagnetically sensitive type, for example a Hall-effect probe. The sensorelement 35 and the active part 18 of the encoder assembly 16 arearranged a very small axial distance away from the rolling bearing 2,particularly from the radial surface 9 b of the inner ring 9, whichgives excellent compactness.

The support body 31 thus extends radially outward from the fixingelement 3.

Furthermore, the support body 31 is provided with a radial outgrowth 31a located circumferentially and forming a cable outlet for a cable 36able to communicate an electrical signal from the sensor element 35 toother elements, not depicted, for example an electronic processing unit.The axial length of the support body 31 is designed such that a smallspace remains between the support 5 and said body 31. This then avoidsdeformation of said support body 31.

It will be understood that the rolling bearing 2, the fixing element 3and the sensor assembly 4 form an instrumented bearing assembly unitwithout the risk of parts being lost and able to be mounted in a simpleand economical way on a support.

In the embodiment of FIG. 3, the fixing element and the support body aremade in one piece of synthetic material, for example fiber-filledmaterial. The bore 20 of the fixing element is plain. The rollingbearing assembly 1 is mounted on a support 37 thicker than the support 5of the previous embodiment. The support 37 is provided with a threadednon-emerging hole 38. A screw 39 has a head 40, an unthreaded body part41 and a threaded end 42. The unthreaded body portion passes through thebore 20. The head 40 is in contact via a washer 43 with the radialannular surface 44 of the fixing element 3 and with the radial annularsurface 9 c of the inner ring 9 of the bearing 2 which is the oppositesurface to the radial annular surface 9 b. The surfaces 9 c and 44 arecoplanar. The threaded end 42 of the screw 40 is screwed into the hole38.

This embodiment has the advantage of an extremely low number of partsand of ease of attachment.

The embodiment illustrated in FIG. 4 is similar to that of FIG. 1 exceptthat a pulley 45 is fixed to the outer ring 7 of the bearing 2. Morespecifically, the pulley 45, of annular shape, has a bore 46 one axialend of which has an annular rib 47 projecting inward. The bore 46 ispush-fitted onto the cylindrical outer surface 7 a of the outer ring,while the rib 47 butts against the radial surface 7 b of the outer ring7, on the side where the sealing flange 14 is. On the opposite side, thepulley 45 has a radial surface 48 roughly aligned with the radial endsurface 9 b of the inner ring 9 and the corresponding surface of theouter ring 7 and which leaves a certain axial space with respect to thesupport body 31.

The pulley 45 comprises an annular rib 49 projecting axially from theside of the support body 31 and arranged radially near the outer ring 7of the bearing 2. The rib 49 may be aligned with the bore 46 of thepulley 45. The rib 49 projects into a corresponding slot 50 formed inthe radial surface 32 of the support body 31. The rib 49 and the slot 50form a chicane providing sealing because of the narrow passage. Sealingthat the encoder and the bearing enjoy is thus improved.

The pulley 45 is provided on its cylindrical outer surface with a groove51 able to collaborate with a vee belt. The radial surface 52 of thepulley 45 on the opposite side to the radial surface 48 projects axiallywith respect to the radial surface 9 c of the inner ring 9 and withrespect to the radial surface 7 b of the outer ring 7. It is thuspossible to make the head of a screw arranged in the bore 20 of thefixing element 3 and arranged in the same direction as the screw 40 ofthe embodiment of FIG. 2 lie flush with said radial surface 52 of thepulley 45 or be set back slightly therefrom, avoiding the creation ofroughnesses.

The pulley 45 may be push-fitted onto the outer ring 7 of the rollingbearing 2 and/or bonded.

In the embodiment illustrated in FIG. 5, the roller with a rollingbearing comprises a rolling bearing 2 identical to the one illustratedin FIG. 1, a fixing element 3, a sensor assembly 4 similar to the oneillustrated in FIG. 1, a pulley 53 and an additional rolling bearing 58.The fixing element 3 is similar to the one illustrated in FIG. 1 exceptthat it is provided with a blind axial hole 20 provided with a threadedportion 21 and that the first cylindrical portion 22 of its outersurface is extended away from the blind hole 20. The fixing element 3 istherefore in the form of an axle provided with a blind hole threaded atone of its axial ends.

The pulley 53 comprises a bore 54 in contact with the cylindrical outersurface 7 a of the outer ring 7 of the bearing 2, a cylindrical outersurface 56 with which a belt or the equivalent can come into contact,and an annular axial outgrowth 55 lying in the continuation of the bore54 and projecting from the frontal radial surface of the pulley 53adjacent to the sensor assembly 4. The annular axial outgrowth 55projects axially into a corresponding annular slot 50 in the supportbody 31.

The spacer piece 57 is of annular shape of parallelepipedal crosssection, having a cylindrical outer surface in contact with the bore 54of the pulley 53, a radial surface in contact with the radial surface 7b of the outer ring 7 of the bearing 2 and an opposite radial surface,and a bore, having a diameter greater than that of the cylindricalportion portion 22 of the fixing element 3. The diameter of the bore ofthe spacer piece 57 is roughly equal to the diameter of the outercylindrical bearing surface of the inner ring 9 of the bearing 2 and maythus contribute to sealing said bearing 2 by forming a narrow passagewith said inner ring 9.

The rolling bearing 58 comprises a rotating outer ring 59 provided witha raceway 60 on its bore, an inner ring 61 provided with a raceway 62 onits outer surface, a row of rolling elements 63, in this case balls,arranged between the raceways 60 and 62 of the outer 59 and inner 61rings, and a cage 54 for maintaining the circumferential spacing of therolling elements 63. The cage 64 may be made of synthetic material or ofsheet metal. The rings 59 and 61 of the bearing 58 are of solid type,produced by machining, but could just as well be made of pressed sheetmetal. The outer ring 59 is provided, on its bore, on each side of theraceway 60, near its radial lateral surfaces, with annular slots 65.Sealing flanges 66 are mounted in the slots 65 and each have a free endextending as far as the vicinity of the outer cylindrical surface of theinner ring 61.

The cylindrical outer surface of the outer ring 59 is in contact withthe bore 54 of the pulley 56, for example as a tight fit. One of theradial lateral surfaces of the outer ring 59 is in contact with thespacer piece 57 on the opposite side to the bearing 2. The inner ring 61is mounted on the cylindrical portion 22 of the fixing element 3, forexample as a tight fit. The axial end of the fixing element 3 projectsvery slightly from the lateral surface of the bearing 58 on the oppositeside to the bearing 2, while the axial end of the pulley 53 projectsslightly from this same lateral surface of the bearing 58.

This embodiment is particularly well suited to applications requiring avery wide pulley and which generally are characterized by relativelyhighly inclined torques. Furthermore, the presence of two rollingbearings in the roller makes it possible to withstand high radial loads.The roller with rolling bearing may be fixed as in the other embodimentsvia the fixing element 3, for example using a screw engaging in thethreaded hole 20. For reasons of economics, the rolling bearing 58 maybe of conventional type, that is to say one acting simply as a bearing.

It would be possible, without departing from the scope of the invention,to anticipate for the fixing element not to have a plain or threadedhole in its central part, but for it to be provided, at its end intendedto be mounted on a support, with a threaded axial part arranged alongthe axis of the device projecting from the radial mounting surface. Saidthreaded axial part can collaborate with a threaded hole in the supportor with a nut.

It will be understood that the sensor support body and the inner ring ofthe rolling bearing are connected rigidly to the fixing element and thatthere can be no relative movement between these two parts.

Thus, in a simple and economical way, there is obtained an instrumentedroller that is extremely compact, that the user need merely installsimply using a screw or a nut and a bolt. All that is then required forthe device to become operational is for the roller to be connected to asignal processing device.

1. A roller device with rolling bearing of the instrumented typesupported by a non-rotating element and provided with a sensor means forsensing rotation parameters and with an encoder means, wherein, thebearing and the sensor means are mounted rigidly on one and the samefixing element able to collaborate with another mechanical member with aview to fixing the device, said fixing element comprising means ofsecuring to said other mechanical member in a central position, and theencoder means is fixed directly to the bearing.
 2. The device as claimedin claim 1, wherein, the fixing element has a cylindrical outer surfacein contact with the bore of an inner ring of the rolling bearing.
 3. Thedevice as claimed in claim 2, wherein, the sensor means comprises anannular support body and at least one sensor element, said body beingarranged in contact with a lateral face of the rolling bearing.
 4. Thedevice as claimed in claim 1, wherein, the fixing element comprises acentral through-hole able to take a screw.
 5. The device as claimed inclaim 4, wherein, the sleeve tube comprises an outer second surface incontact with an inner surface of the sensor means and a radial surfacein contact with a radial surface of the inner ring of the rollingbearing.
 6. The device as claimed in claim 5, wherein, the fixingelement is provided with a plain or threaded bore for fixing the deviceto another mechanical member.
 7. The device as claimed in claim 4,wherein, the fixing element is provided with a plain or threaded borefor fixing the device to another mechanical member.
 8. The device asclaimed in claim 1, wherein, the sensor means comprises an annularsupport body and at least one sensor element, said body being arrangedin contact with a lateral face of the rolling bearing.
 9. The device asclaimed in claim 1, wherein, the encoder means is provided with asupport and with an active part, the active part projecting from alateral face of the rolling bearing, the support being fixed directly tothe bearing, the active part being arranged radially at the rollingelements.
 10. The device as claimed in claim 1, wherein, the encodermeans and the sensor means are mounted in close proximity to a lateralface of the rolling bearing.
 11. The device as claimed in claim 1,wherein, the fixing element comprises a radial surface for mounting on asupport, the encoder means being arranged axially between said radialmounting surface and the rolling bearing.
 12. The device as claimed inclaim 1, wherein, the support body is provided with a radial lateralsurface in which there is formed an annular slot comprising acylindrical outer surface, the sensor element lying flush with saidcylindrical outer surface.